How do I get rid of the white worms that are attacking the roots of my broccoli?
These small, white maggots like to attack the roots of broccoli, cauliflower, Brussels sprouts, turnips, radishes, mustards and just about any other member of the cabbage family and once they take a liking to your garden, they have a habit of becoming regular visitors.
The maggots destroy their victim plants by tunnelling into their roots, which causes the above-ground parts to first wilt then die. Sometimes this decline is a direct result of the damage caused by the larvae and other times it's because the larvae opens up an avenue for diseases to enter the plant.
Either way, it isn't good.
Since eradicating root maggots once they become established can be next to impossible, your efforts are better spent trying to prevent the adult flies from laying their eggs. This gets around the tricky business of trying to kill the maggots themselves, which is a difficult thing to do especially since very few substances are registered to control them and those which are really aren't the sort of things that you want to be spraying on a food crop.
One thing you can do to protect your plants from infestation is to make sure that the adult flies can't get anywhere near them by setting out floating row covers as soon as you stick your transplants in the ground each spring and keeping them in place until harvest time.
Another solution is to surround the base of your plants with tar paper, which will keep the flies from laying their eggs in the ground and no eggs mean no larvae which in turn mean no problem.
Sticky traps are sometimes used to catch the flies, but it's questionable whether this method can catch enough of the flies to be truly effective and these traps also tend to catch other bugs, some of which are beneficial.
Other helpful practices include rotating your crops so that members of the cabbage family are never planted in the same soil two years in a row and removing any diseased or infested plant material from your property.
In some cases, parasitic nematodes can be helpful when physical barriers fail as long as they are applied after the soil has warmed up to a stable 12C, otherwise they will be ineffective.
If you have any questions or comments, please send them to me at vanessa@gardenmuse.ca.
Originally published in the Creston Valley Advance on August 5, 2010.
